diff --git a/sqlite3.go b/sqlite3.go
index d56bed3..2179cf2 100644
--- a/sqlite3.go
+++ b/sqlite3.go
@@ -586,7 +586,7 @@ func errorString(err Error) string {
 //   file:test.db?cache=shared&mode=memory
 //   :memory:
 //   file::memory:
-// go-sqlite handle especially query parameters.
+// go-sqlite3 adds the following query parameters to those used by SQLite:
 //   _loc=XXX
 //     Specify location of time format. It's possible to specify "auto".
 //   _busy_timeout=XXX
diff --git a/sqlite3_fts3_test.go b/sqlite3_fts3_test.go
index 884ca4c..beb5ada 100644
--- a/sqlite3_fts3_test.go
+++ b/sqlite3_fts3_test.go
@@ -12,7 +12,7 @@ import (
 )
 
 func TestFTS3(t *testing.T) {
-	tempFilename := TempFilename()
+	tempFilename := TempFilename(t)
 	db, err := sql.Open("sqlite3", tempFilename)
 	if err != nil {
 		t.Fatal("Failed to open database:", err)
diff --git a/sqlite3_test.go b/sqlite3_test.go
index 0239c78..90bee51 100644
--- a/sqlite3_test.go
+++ b/sqlite3_test.go
@@ -6,12 +6,11 @@
 package sqlite3
 
 import (
-	"crypto/rand"
 	"database/sql"
 	"database/sql/driver"
-	"encoding/hex"
 	"errors"
 	"fmt"
+	"io/ioutil"
 	"net/url"
 	"os"
 	"path/filepath"
@@ -25,15 +24,19 @@ import (
 	"github.com/mattn/go-sqlite3/sqlite3_test"
 )
 
-func TempFilename() string {
-	randBytes := make([]byte, 16)
-	rand.Read(randBytes)
-	return filepath.Join(os.TempDir(), "foo"+hex.EncodeToString(randBytes)+".db")
+func TempFilename(t *testing.T) string {
+	f, err := ioutil.TempFile("", "go-sqlite3-test-")
+	if err != nil {
+		t.Fatal(err)
+	}
+	f.Close()
+	return f.Name()
 }
 
 func doTestOpen(t *testing.T, option string) (string, error) {
 	var url string
-	tempFilename := TempFilename()
+	tempFilename := TempFilename(t)
+	defer os.Remove(tempFilename)
 	if option != "" {
 		url = tempFilename + option
 	} else {
@@ -84,8 +87,29 @@ func TestOpen(t *testing.T) {
 	}
 }
 
+func TestReadonly(t *testing.T) {
+	tempFilename := TempFilename(t)
+	defer os.Remove(tempFilename)
+
+	db1, err := sql.Open("sqlite3", "file:"+tempFilename)
+	if err != nil {
+		t.Fatal(err)
+	}
+	db1.Exec("CREATE TABLE test (x int, y float)")
+
+	db2, err := sql.Open("sqlite3", "file:"+tempFilename+"?mode=ro")
+	if err != nil {
+		t.Fatal(err)
+	}
+	_ = db2
+	_, err = db2.Exec("INSERT INTO test VALUES (1, 3.14)")
+	if err == nil {
+		t.Fatal("didn't expect INSERT into read-only database to work")
+	}
+}
+
 func TestClose(t *testing.T) {
-	tempFilename := TempFilename()
+	tempFilename := TempFilename(t)
 	db, err := sql.Open("sqlite3", tempFilename)
 	if err != nil {
 		t.Fatal("Failed to open database:", err)
@@ -111,7 +135,7 @@ func TestClose(t *testing.T) {
 }
 
 func TestInsert(t *testing.T) {
-	tempFilename := TempFilename()
+	tempFilename := TempFilename(t)
 	db, err := sql.Open("sqlite3", tempFilename)
 	if err != nil {
 		t.Fatal("Failed to open database:", err)
@@ -150,7 +174,7 @@ func TestInsert(t *testing.T) {
 }
 
 func TestUpdate(t *testing.T) {
-	tempFilename := TempFilename()
+	tempFilename := TempFilename(t)
 	db, err := sql.Open("sqlite3", tempFilename)
 	if err != nil {
 		t.Fatal("Failed to open database:", err)
@@ -215,7 +239,7 @@ func TestUpdate(t *testing.T) {
 }
 
 func TestDelete(t *testing.T) {
-	tempFilename := TempFilename()
+	tempFilename := TempFilename(t)
 	db, err := sql.Open("sqlite3", tempFilename)
 	if err != nil {
 		t.Fatal("Failed to open database:", err)
@@ -276,7 +300,7 @@ func TestDelete(t *testing.T) {
 }
 
 func TestBooleanRoundtrip(t *testing.T) {
-	tempFilename := TempFilename()
+	tempFilename := TempFilename(t)
 	db, err := sql.Open("sqlite3", tempFilename)
 	if err != nil {
 		t.Fatal("Failed to open database:", err)
@@ -325,7 +349,7 @@ func TestBooleanRoundtrip(t *testing.T) {
 }
 
 func TestTimestamp(t *testing.T) {
-	tempFilename := TempFilename()
+	tempFilename := TempFilename(t)
 	db, err := sql.Open("sqlite3", tempFilename)
 	if err != nil {
 		t.Fatal("Failed to open database:", err)
@@ -408,7 +432,7 @@ func TestTimestamp(t *testing.T) {
 }
 
 func TestBoolean(t *testing.T) {
-	tempFilename := TempFilename()
+	tempFilename := TempFilename(t)
 	db, err := sql.Open("sqlite3", tempFilename)
 	if err != nil {
 		t.Fatal("Failed to open database:", err)
@@ -500,7 +524,7 @@ func TestBoolean(t *testing.T) {
 }
 
 func TestFloat32(t *testing.T) {
-	tempFilename := TempFilename()
+	tempFilename := TempFilename(t)
 	db, err := sql.Open("sqlite3", tempFilename)
 	if err != nil {
 		t.Fatal("Failed to open database:", err)
@@ -538,7 +562,7 @@ func TestFloat32(t *testing.T) {
 }
 
 func TestNull(t *testing.T) {
-	tempFilename := TempFilename()
+	tempFilename := TempFilename(t)
 	db, err := sql.Open("sqlite3", tempFilename)
 	if err != nil {
 		t.Fatal("Failed to open database:", err)
@@ -570,7 +594,7 @@ func TestNull(t *testing.T) {
 }
 
 func TestTransaction(t *testing.T) {
-	tempFilename := TempFilename()
+	tempFilename := TempFilename(t)
 	db, err := sql.Open("sqlite3", tempFilename)
 	if err != nil {
 		t.Fatal("Failed to open database:", err)
@@ -630,7 +654,7 @@ func TestTransaction(t *testing.T) {
 }
 
 func TestWAL(t *testing.T) {
-	tempFilename := TempFilename()
+	tempFilename := TempFilename(t)
 	db, err := sql.Open("sqlite3", tempFilename)
 	if err != nil {
 		t.Fatal("Failed to open database:", err)
@@ -678,7 +702,7 @@ func TestWAL(t *testing.T) {
 func TestTimezoneConversion(t *testing.T) {
 	zones := []string{"UTC", "US/Central", "US/Pacific", "Local"}
 	for _, tz := range zones {
-		tempFilename := TempFilename()
+		tempFilename := TempFilename(t)
 		db, err := sql.Open("sqlite3", tempFilename+"?_loc="+url.QueryEscape(tz))
 		if err != nil {
 			t.Fatal("Failed to open database:", err)
@@ -786,7 +810,7 @@ func TestSuite(t *testing.T) {
 // TODO: Execer & Queryer currently disabled
 // https://github.com/mattn/go-sqlite3/issues/82
 func TestExecer(t *testing.T) {
-	tempFilename := TempFilename()
+	tempFilename := TempFilename(t)
 	db, err := sql.Open("sqlite3", tempFilename)
 	if err != nil {
 		t.Fatal("Failed to open database:", err)
@@ -806,7 +830,7 @@ func TestExecer(t *testing.T) {
 }
 
 func TestQueryer(t *testing.T) {
-	tempFilename := TempFilename()
+	tempFilename := TempFilename(t)
 	db, err := sql.Open("sqlite3", tempFilename)
 	if err != nil {
 		t.Fatal("Failed to open database:", err)
@@ -847,7 +871,7 @@ func TestQueryer(t *testing.T) {
 }
 
 func TestStress(t *testing.T) {
-	tempFilename := TempFilename()
+	tempFilename := TempFilename(t)
 	db, err := sql.Open("sqlite3", tempFilename)
 	if err != nil {
 		t.Fatal("Failed to open database:", err)
@@ -885,7 +909,7 @@ func TestStress(t *testing.T) {
 
 func TestDateTimeLocal(t *testing.T) {
 	zone := "Asia/Tokyo"
-	tempFilename := TempFilename()
+	tempFilename := TempFilename(t)
 	db, err := sql.Open("sqlite3", tempFilename+"?_loc="+zone)
 	if err != nil {
 		t.Fatal("Failed to open database:", err)
@@ -952,7 +976,7 @@ func TestVersion(t *testing.T) {
 }
 
 func TestNumberNamedParams(t *testing.T) {
-	tempFilename := TempFilename()
+	tempFilename := TempFilename(t)
 	db, err := sql.Open("sqlite3", tempFilename)
 	if err != nil {
 		t.Fatal("Failed to open database:", err)
@@ -988,7 +1012,7 @@ func TestNumberNamedParams(t *testing.T) {
 }
 
 func TestStringContainingZero(t *testing.T) {
-	tempFilename := TempFilename()
+	tempFilename := TempFilename(t)
 	db, err := sql.Open("sqlite3", tempFilename)
 	if err != nil {
 		t.Fatal("Failed to open database:", err)
@@ -1048,7 +1072,7 @@ func (t TimeStamp) Value() (driver.Value, error) {
 }
 
 func TestDateTimeNow(t *testing.T) {
-	tempFilename := TempFilename()
+	tempFilename := TempFilename(t)
 	db, err := sql.Open("sqlite3", tempFilename)
 	if err != nil {
 		t.Fatal("Failed to open database:", err)
diff --git a/sqlite3_test/sqltest.go b/sqlite3_test/sqltest.go
index 782e15f..84b65d9 100644
--- a/sqlite3_test/sqltest.go
+++ b/sqlite3_test/sqltest.go
@@ -275,12 +275,11 @@ func TestPreparedStmt(t *testing.T) {
 	}
 
 	const nRuns = 10
-	ch := make(chan bool)
+	var wg sync.WaitGroup
 	for i := 0; i < nRuns; i++ {
+		wg.Add(1)
 		go func() {
-			defer func() {
-				ch <- true
-			}()
+			defer wg.Done()
 			for j := 0; j < 10; j++ {
 				count := 0
 				if err := sel.QueryRow().Scan(&count); err != nil && err != sql.ErrNoRows {
@@ -294,9 +293,7 @@ func TestPreparedStmt(t *testing.T) {
 			}
 		}()
 	}
-	for i := 0; i < nRuns; i++ {
-		<-ch
-	}
+	wg.Wait()
 }
 
 // Benchmarks need to use panic() since b.Error errors are lost when